diff --git a/mlir/lib/ExecutionEngine/SparseTensor/File.cpp b/mlir/lib/ExecutionEngine/SparseTensor/File.cpp
--- a/mlir/lib/ExecutionEngine/SparseTensor/File.cpp
+++ b/mlir/lib/ExecutionEngine/SparseTensor/File.cpp
@@ -24,6 +24,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "mlir/ExecutionEngine/SparseTensor/File.h"
+#include "llvm/Support/ErrorHandling.h"
 
 #include <cctype>
 #include <cstring>
@@ -108,6 +109,7 @@
     // integer and floating primary-types.
     return isRealPrimaryType(valTy);
   }
+  llvm_unreachable("unknown ValueKind");
 }
 
 /// Helper to convert C-style strings (i.e., '\0' terminated) to lower case.